This invention relates to a quick disconnect coupling, and, more particularly, to a coupling used in connection with pressurized fluid. For example, agricultural tractors have a quick disconnect coupling for connecting and disconnecting hydraulic hoses between the tractor and a hydraulically operated implement. The agricultural tractor provides the power source to operate the implement hydraulic components. Hydraulic hoses connect the tractor power source to the implement hydraulic system. Quick disconnect couplings are used on the hydraulic hoses to enable disconnecting the implement from the tractor. The female half of the coupling is mounted on the tractor, and the male half of the coupling is on the implement hoses.
Because of the variety of operating conditions on agricultural applications, the coupling must often function under unique conditions and perform special functions not normal to conventional quick disconnect couplings. Some of these functions include withstanding high surge flows of oil (as high as four times the normal flow rate is common) and connecting and disconnecting while the hoses are pressurized and/or flowing oil.
Some prior art couplings, for example, those described in U.S. Pat. Nos. 3,431,942, 3,530,887, and 3,646,964, perform these functions, but these couplings have the following limitations and problems:
1. The shrouding around the valves creates a low pressure area behind the valve during disconnect. This retards the closing of the valves when disconnecting, and causes an oil spray or excessive oil spillage.
2. Some designs overcome the situation described above by increasing the clearances between the shroud and the valves. This corrects the closing problem but creates another problem. The increased clearance reduces the guiding ability of the shroud. Then the valve will not center on the seat during closing.
3. The long tubular internal parts are expensive to machine from solid material.
The invention provides a quick disconnecting coupling which solves all of the foregoing problems. The female coupling includes a poppet which is slidably mounted within a shroud, and the poppet includes a guide portion having a hexagonally shaped periphery which guides the sliding movement of the poppet within the shroud. The rounded corners of the hexagonal guide portion provide close guiding in the bore of the shroud to center the poppet, and the flats of the hexagon provide flow passages which permit oil to reach the back side of the poppet quickly when disconnecting. The long parts of the poppet are formed inexpensively by deep drawing from sheet stock rather than machining. The male coupling includes a deep drawn shroud which is provided with radially enlarged dimples which permit oil to flow past the ball valve of the coupling when disconnecting.